A puzzle, if you will

[will.koch]

My bronco was running fine, but having a little trouble starting up... I changed the spark plugs, wires, cap, and rotor, and it then started to miss (which actually coincided with the weather warming up).... I saw air bubbles in my inline fuel filter, and so I rerouted the fuel line further away from the exhaust. This seemed to fix the problem... sort of... Now, I drive it 5 miles to work, and if I turn around and drive it right back, it misses just like it used to about half way back. In other words, after my temperature guage has been reading 190 or so for a certain amount of time, it starts missing...

Furthermore, I am losing quite a bit of oil, but there is no noticable blue smoke coming from the exhaust or around the engine.

Currently, the symptoms are: backfire at the carb while starting, missing after engine has warmed up, been stopped, and started and driven again... and its losing a lot of oil...

Can anybody offer me a good path to take in fixing this thing?

 

[Seabronc]

The run problem sounds like a timing problem. It could be off by a tooth or the timing chain may be worn. As far as the oil goes /emoticons/[email protected] 2x" width="20" height="20" /> , if it is not burning it, then it must be dripping some place. Does your engine have the PCV system have intake air from a small filter in the air cleaner? Then from the PCV valve to the base of the carb? If you have excessive blow by from worn cylinders it will pressureize the crank case enough to push oil back up into the intake. That probably wouldn't be noticed in exhaust as it is not like a ring problem where a larger quantity of oil would be burned. Hope that makes sense, if not read the comment in my signature /emoticons/[email protected] 2x" width="20" height="20" /> .

Good luck,

>-

 

[will.koch]

Does the timing problem explain why its missing only after being hot for a certain amount of time? My temperature only reaches about 190, at best.. But after its there for a while, I think is when it really misses, almost to the point of not being able to drive down a flat road. Also, there is noticable oil seapage around the PCV hose, and the back half of that valve cover. Do you think blow by would also be causing the missing while hot?

Thanks a bunch for your help.

-Will

 

[Seabronc]

Currently, the symptoms are: backfire at the carb while starting, missing after engine has warmed up, been stopped, and started and driven again... and its losing a lot of oil...

That is the main reason I said something about timing and yes being hot could have an effect on it. It might also be a completely different problem from the start up problem. Fix the obvious first and if you still have another problem then fix that. If you have multiple problems the symptoms tend to be confusing, especially if you are trying to relate them all to a single cause. You may also have fuel vaporization problems or an air leak in the fuel line. I'll post a picture with this of a air leak I had caused which was caused by a mouse chewing on the rubber part of the fuel line. He quit when he got a taste of gas. It didn't leak but sucked air into the fuel line when the engine was running.

Good luck,

>-

 

[will.koch]

Fred,

We found the hose on the vacuum advance to be intermittent. I think it was warming up and expanding and killing the vacuum. We put a hose clamp on and it seems to help a bunch. I'll probably replace the hose all together in the next few days. I appreciate your help and pointing us in the right direction.

Respectfully,

Will